std.experimental.logger formal review round 3

[via Digitalmars-d]

On Wednesday, 12 November 2014 at 12:39:24 UTC, Robert burner 
Schadek wrote:
> Only one thread can write to one Logger at a time, also known 
> as synchronization. Anything else is properly wrong. But you 
> can have as many Logger as you have memory.

Taking a lock when the logging call doesn't flush to disk sounds 
rather expensive.